Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Debate Wisdom of Plan to Save Venice From Flooding

10.05.2002


The Italian government recently decided to move forward with planning for the construction of underwater, mobile floodgates to mitigate flooding in Venice, situated on islands in a lagoon in the Adriatic Sea. The soundness of the plan is discussed by several scientists in the May 14 issue of Eos, published by the American Geophysical Union.



The approved plan to protect Venice, called MOSE (Modulo Sperimentale Elettromeccanico, or Experimental Electromechanical Module), involves the construction of 79 gates at three lagoon inlets. When waters rise 1.1 meters [43 inches] above "normal," air will be injected into the hollow gates, causing them to rise, blocking seawater from entering the lagoon and thereby preventing the flooding of Venice. The floodgates will take approximately eight years and $2.6 billion to construct.

Some critics of MOSE, such as Paolo Antonio Pirazzoli of the French Centre National de la Recherche Scientifique (CNRS), are skeptical as to whether the gates will actually prevent flooding. In his Eos article, Pirazzoli states that the design of the gates is based on outdated predictions of sea-level change, utilizing a scenario that differs by nearly 0.26 meters [10 inches] from recent estimates of rise in sea level over the next century, made by the Intergovernmental Panel on Climate Change (IPCC). Pirazzoli also
asserts that the MOSE designers did not consider sea-level rise associated with land subsidence or increased water levels associated with extended rainy or windy periods.



Pirazzoli argues that once sea-level rise exceeds 0.31 meters [1 foot], possibly within the next 100 years, MOSE will become obsolete and will need to be replaced with watertight gates. Therefore, Pirazzoli contends, the Italian government should follow "soft" techniques, such as raising street level elevations, and await further assessment of sea-level rise to find "an updated, wise solution, more able to cope with foreseeable sea-level change."

In the same issue of Eos, MOSE supporters Rafael L. Bras, Donald R.F. Harleman, and Paola Rizzoli of the Massachusetts Institute of Technology, comment on Pirazzoli`s view. The writers, who worked on the design and assessment of MOSE, state that the gates will indeed be effective barriers to flooding. They note that the sea-level rise scenario they utilized was based on recent research and that the floodgates are designed to prevent flooding in the event of a 0.3 to 0.5-meter [12 to 20 inch] rise in sea level. Furthermore, they say, it is not necessary to consider further land subsidence, because it was the result of groundwater removal that was ended in the 1970s, and it has not been a problem since then.

Bras and his colleagues note that as flooding occurs with greater frequency, steps will have to be taken to protect the city, and the cost of doing nothing may be greater than the cost of constructing the MOSE gates. They believe that, "the barriers, as designed, separate the lagoon from the sea in an effective, efficient and flexible way, considering present and foreseeable scenarios." With regard to Pirazzoli`s contention that the mobile floodgates would eventually have to be replaced with watertight gates, they respond that if water levels continue to rise, the gates would just remain closed more often, in effect serving as "permanent" barriers.

Environmentalists argue, however, that keeping the gates closed for increasingly longer periods of time could be detrimental to the lagoon`s ecosystem, which relies on exchange of waters between the lagoon and the Adriatic Sea to flush pollutants from the lagoon. Without this cleansing flow, they say, toxic substances may build up in lagoon waters, damaging its delicate ecosystem.

In order to understand how frequent closing of the gates would impact the lagoon`s ecosystem, it is necessary to understand water flow patterns and exchange rates through the lagoon inlets. Miroslav Gacic and colleagues have taken preliminary steps in addressing these issues. Their research, published in the same edition of Eos, is based on a series of ship-borne surveys of water flowing through the inlet over an approximately forty-five day period.

Although the results are preliminary, the authors conclude that flow through the inlets is controlled primarily by tides. They also determine that the lagoon waters have an exchange rate of about one day, meaning that the lagoon is well-ventilated and quickly flushed. The researchers note that better assessments will be made when data representing several seasons become available.

Harvey Leifert | alphagalileo

More articles from Ecology, The Environment and Conservation:

nachricht Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Extensive Funding for Research on Chromatin, Adrenal Gland, and Cancer Therapy

28.06.2017 | Awards Funding

Predicting eruptions using satellites and math

28.06.2017 | Earth Sciences

Extremely fine measurements of motion in orbiting supermassive black holes

28.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>